> sometimes also had to interrupt
> the copying process. After finishing the operation I
> saw many *.html.tmp files
> (almost every html file has a copy with .tmp
> extension). Can I safely delete
> files having html.tmp extension? Is there any
> dependencies? 

You interrupted it. Why don't you expect temporary files to remain.
Yes you can delete them, or just continue the mirror and it will take care of
them itself.